Switch fake-sys submodule from rhempel to ddemidov (#397)

* Switch fake-sys submodule from rhempel to ddemidov

* Updated to latest fake-sys

* Fix board_info_dir for FAKE_SYS

Author: dwalton76

.gitmodules

@@ -1,3 +1,3 @@
 [submodule "tests/fake-sys"]
 	path = tests/fake-sys
-	url = https://github.com/rhempel/ev3dev-lang-fake-sys.git
+	url = https://github.com/ddemidov/ev3dev-lang-fake-sys.git

ev3dev/__init__.py

@@ -48,6 +48,9 @@ def get_current_platform():
     """
     board_info_dir = '/sys/class/board-info/'
 
+    if not os.path.exists(board_info_dir):
+        return 'fake'
+
     for board in os.listdir(board_info_dir):
         uevent_filename = os.path.join(board_info_dir, board, 'uevent')
 

ev3dev/sensor/lego.py

@@ -29,7 +29,7 @@
     raise SystemError('Must be using Python 3.4 or higher')
 
 import time
-from ev3dev._button import ButtonBase
+from ev3dev.button import ButtonBase
 from ev3dev.sensor import Sensor